1. Field of the Application
This application relates generally to test and diagnostic systems for equipment under diagnosis, particularly motor vehicles. More specifically, the application relates to an automated process for retrieving diagnostic information relative to returned trouble codes from one or more equipment components under diagnosis. While the application is described in the context of a motor vehicle diagnostic system and method, the principles of the present application are equally applicable for any testing and diagnostic systems, including non-motor vehicle equipment, as long as the equipment under diagnosis stores trouble codes relative to a past or current error condition.
2. Description of the Related Art
Motor vehicles are becoming highly computerized products. In recent years, for example, the control of internal combustion engines has branched away from traditional mechanical linkages and analog approaches to electronic or microprocessor-based control systems. In a typical modern motor vehicle, the operation of the combustion engine is controlled by an engine control module (ECM) which receives a variety of input signals and outputs signals for monitoring and controlling various components of the engine. For example, the ECM can send signals to a fuel system for controlling the air/fuel mix sent to the engine cylinders. The ECM may also receive and store signals from various sensors throughout the engine, drive train, braking system, exhaust system, heating and cooling systems, and braking systems. For example, the sensors may provide signals indicative of engine speed, fuel/air mix, intake and exhaust pressure, engine operating temperatures, fluid levels, activation of anti-lock brakes (ABS), and the like that may be monitored and/or stored by the ECM.
The ECM may retain a portion of the data in memory as historical data, providing a detailed history of equipment performance, operating parameters, and error indicators. An external interface to the ECM and its stored data is provided at a location accessible to a repair technician. The information stored in the ECM can be downloaded via the external interface at predetermined intervals in the equipment life, when there are noticeable degradations in equipment performance, or when critical trouble codes are received and externally indicated to an operator of the equipment. The downloaded information can then be analyzed by a repair technician to evaluate the equipment performance or error conditions, and thereby make informed recommendations for servicing of the equipment.
In order to facilitate the retrieval of trouble codes and diagnostic information from an ECM or similar circuit, a number of different types of trouble code retrieval tools have been developed to assist in the diagnosis and repair of fault conditions reported by the ECM's and other similar circuits. Such a retrieval tool can typically be connected to the ECM's external interface and may provide the data, via a wired or wireless connection, to a diagnostic tool for displaying the data stored in the ECM visually to the repair technician, or for furthering processing. For example, a retrieval tool may obtain one or more pieces of information about the vehicle's engine noted above, including fluid levels, operating temperatures, fuel/air mixes, in addition to other information reported by the transmission, air conditioning, braking, and/or power systems.
Once the error codes are retrieved, a repair technician must determine a course of action to further diagnose a problem represented by the one or more trouble codes and/or repair the underlying problem represented by the one or more trouble codes.
Manufacturers typically publish repair manuals, including diagnostic trees, exploded part diagrams, and the like, to aid the repair technician in the diagnosis and repair of problems associated with the retrieved trouble code(s). Repair manuals are normally published separately for each piece of equipment. For example, based upon selected faults, a published diagnostic tree for a particular motor vehicle engine model could present the reader with a list of tests to be performed to diagnose the cause or causes of the faults particular to that model. The tests can be listed in the order in which they would most likely be effective in diagnosing the faults, based upon a manufacturer's information and previous repair and diagnosis experience with this type of equipment, for example. The repair manuals may be available in hard copy or accessible via the Internet in a computer viewable format.
In practice, a repair technician then navigates through the repair information in order to find the information pertinent to the specific equipment being diagnosed. Though technicians normally see this activity as a part of their job, it can be a time consuming process. The time element increases a cost of repair and delays the turnaround time for returning the motor vehicle under repair to service. This is especially important in the trucking industry, where a truck must be on the road to be generating income, or where a disabled truck is carrying a time-sensitive load such as perishable food.